Doctor Who is gearing up for its Season 11 finale, and for the first time in what feels like a long time, fans may have reason to suspect something established and familiar is on the horizon. Speculation currently abounds after the penultimate episode’s “Next Time” teaser featured a voiceover that sounded a lot like a villain viewers have heard from before. So, is the Stenza warrior T’zim-Sha heading back to Doctor Who for the season finale?

Alien T’zim-Sha (or Tim Shaw) seems to be the most likely candidate at the moment, as a guttural voice is heard in the teaser saying “You gave me my destiny” before things move on. While the jury’s still out on the Doctor granting him a “destiny,” she did give the Stenza assassin a chance to escape a gruesome death in the Doctor Who Season 11 opener.

We haven’t seen him since then, though the warrior race did get a mention in a previous episode, causing many to theorize that the Setnza would become more important in Season 11 and beyond. So perhaps T’zim-Sha’s spared life resulted in a noteworthy journey that led him back to Eleven?

There are other candidates as to who this mystery person may be, as Doctor Who has villains like Dalek creator Davros whose voice hits around that vocal register. That said, bringing back a deep-lore villain would go against this season’s theme of introducing new Doctor Who elements,. Of course, so would the return of one of Season 11’s new villains. Still, it seems more probable that Chibnall would pull a villain from his own run rather than one from prior seasons.

As previously mentioned, Tzim-Sha’s Stenza race is one of the only species that has been mentioned more than once within the season. That next mention came in “The Ghost Monument” when it was revealed the Stenza were behind the “cleansing” of a character’s planet which resulted in a mass execution. Tzim-Sha’s re-emergence in the finale would tie together a season that’s felt largely episodic and disconnected so far, helpings things come full circle in as only Who can.

Tzim-Sha may not be the only character coming back for Doctor Who‘s Season 11 finale, however. The episode’s full promo teased another voice that that was familiar to the Doctor, if not everyone. The voice, which sounded female, can be heard screaming in a way one could usually interpret as a cry for help.

That certainly doesn’t seem like the sort of scream a Stenza warrior would make, so it would appear two familiar faces could be surfacing before Season 11 bows out. Obviously, there’s a long list of characters who the Doctor could be referring to, so it’s almost impossible to rule anyone out for a return. Especially given how sneaky Doctor Who can be with surprise cameos, fans may be getting the appearance of a character that no one may expect.

Mysteries will be revealed when Doctor Who airs its Season 11 finale on BBC America Sunday, December, 9 at 8:00 p.m. ET. After that, fans will still have the holiday special to look forward to on New Year’s day, as well as some other programming that can be found on our fall and midseason premiere guides.